My primary research interest is biogeochemistry in aquatic ecosystems. I have developed a method to study nitrogen cycling processes in rivers at the whole-reach scale using mass spectrometry to measure dissolved nitrogen gases with high precision and accuracy. This is the only current method that measures denitrification directly at a scale appropriate for testing factors that control this process. Denitrification, the microbial reduction of nitrate to N2, represents the only permanent sink for nitrogen and could control eutrophication of coastal ecosystems. I am also applying this method to measure production of other biogenic gases in rivers, such as nitrous oxide and methane, important greenhouse gases. I am involved in a related project with researchers in China to study nitrogen and carbon cycling in the Changjiang (Yangtze) River, with emphasis on the role of the newly constructed and controversial Three Gorges Dam. This research is in collaboration with Sybil Seitzinger at Rutgers University and Weijin Yan at the Chinese Academy of Science. Another area of my research is microbial ecology. I am using denaturing gradient gel electrophoresis (DGGE) to gain detailed information about the community structure of microbial communities. I am using multivariate statistical models to determine relationships between microbial community structure and biogeochemical processes, demonstrating that microbial community composition can control ecosystem function. This research is in collaboration with Charles Kulpa at the University of Notre Dame. Another ongoing microbial ecology project is the degradation of crude oil by various microbial consortia and pure cultures. This research could have significance in predicting the fate of oil spills in natural environments and in applications to enhance bioremediation. This research is in collaboration with Charles Kulpa and Yongsong Huang at Brown University.

I study ecosystem ecology to better understand how natural ecosystems function and how they will respond to disturbances

Up to five areas of research specialization (in point form) - Nitrogen and carbon biogeochemistry - Aquatic ecology - Microbial ecology - Ecosystem modeling - Ecotoxicology

Smith, T.E., A.E. Laursen, and J.R. Deacon (2008) Nitrogen attenuation in the Connecticut River, northeastern USA; a comparison of mass balance and N2 production modeling approaches. Biogeochemistry 87:311-323.

Laursen, A.E., C.F. Kulpa, Jr., M. Niedzielski, and M. Estable (2007) Bacterial cultures capable of facultative growth on methane under thermophilic or thermotolerant conditions. Journal of Environmental Engineering and Science 6:643-650.

Laursen, A.E., and S.P. Seitzinger (2005) Limitations to measuring riverine denitrification at the whole-reach scale: effects of channel geometry, wind velocity, sampling interval, and temperature and inputs of N2-enriched groundwater. Hydrobiologia 545:225-236.